Continuous casting mold with coated jacket under spring tensioning

ABSTRACT

A mold for continuous casting of metal has a graphite body which surrounds an elongated mold cavity. A metallic jacket surrounds the graphite body in engagement with the circumferential outer surface thereof, and the jacket is subdivided circumferentially of the surface into at least two jacket sections. Pressure means is associated with the jacket sections and draws the same together circumferentially of the graphite body to thereby urge the jacket into intimate surface-to-surface contact with the circumferential surface of the graphite body and subject the latter to radially inwardly directed pressure over the entire area of the circumferential surface.

United States Patent 72] Inventor Hans Wieland Ulm, Germany [21] Appl. No. 813,582 [22] Filed Apr. 4, 1969 I45] Patented Aug. 17,1971 I73] Assignee Wleland-Werke AG Ulm, Germany [32] Priority Apr., 1968 [33] Germany [31] P17581576 [54] CONTINUOUS CASTING MOLD WITH COATED JACKET UNDER SPRING TENSIONING [56] References Cited Primary Examiner Robert D. Baldwin Attorney-Michael S. Striker ABSTRACT: A mold for continuous casting of metal has a graphite body which surrounds an elongated mold cavity. A metallic jacket surrounds the graphite body in engagement with the circumferential outer surface thereof, and the jacket is subdivided circumferentially of the surface into at least two jacket sections. Pressure means is associated with the jacket sections and draws the same together circumferentially of the graphite body to thereby urge the jacket into intimate surfaceto-surface contact with the circumferential surface of the graphite body and subject the latter to radially inwardly directed pressure over the entire areaof the circumferential surface.

PATENTED AUG] 7 I97! SHEET 2 OF 3 R 9 m m a r u M m tm s M w v |..r H

CONTINUOUS CASTING MOLD WITH COATED JACKET UNDER SPRING TENSIONING BACKGROUND OF THE INVENTION metal, molds which consist of a cooled outer metallic jacket and an insert within this jacket, the insert being made of grajacent jacket sections-of which there may be more than two provided-overlap one another to obtain a continuous coverage of the outer circumferential surface of the graphite phite and surrounding and defining the mold cavity in which the metal is cast. The purpose of using graphite for surrounding and defining the mold cavity is the utilization of the lubricating effect of the graphite body or insert. However, this effect will be negated if the graphite is allowed to burn and undergo gradual oxidation under the influence of the heat of the molten metal. Therefore it is known to cool the metal jacket and through the same the graphite insert.

. In order to assure quick heat exchange between the cooled metallic jacket and the graphite insert, intimate contact must be maintained between the two. In certain applications, and with certain configurations of the mold cavity, it'is-very difficult to maintain this requisite contact. Unless this is possible,

I however, the advantageof the high casting speed which 'is obtainable by employing thegraphite insert in the first place, is nullified by the necessity to efiect frequent repairs and by the attendant downtime in the casting operation.

To overcome this problem it is known from US. Pat. No. 3,412,784 to I-Ians Wieland, to mount'the cooled metallic jacket on the outer peripheral surface of the graphite insert under tangential tension so as to exert compressive forces in radial direction upon the graphite insert at all points of its peripheral surface. This assures that all points of the outer surface of the graphite insert will at all times be in intimate contact with the metallic jacket, whereby the best and most rapid heat exchange is assured at all times between the graphite insert and'the metallic jacket which in turn is being cooled.

While this construction, set forth in U.S. Pat. No. 3,412,784, has been found to be highly efficient, it has also been found that further improvements'in the mounting of the metal jacket on the graphite insert are not only desirable but also possible.

SUMMARY OF THE INVENTION It is, accordingly, the general object of the present invention to provide such improvements.

More particularly, it is an object of the present invention to provide a continuous casting mold of the type under discussion wherein the tangential forces exerted by the cooled metal jacket are adjustable and can be regulated at the will of an operator in dependence upon the given operating conditions which apply to the mold.

In pursuance of the above objects, and others which will become apparent hereafter, one feature of my invention resides in the provision of a mold for the continuous casting of metal, which mold comprises a graphite body surrounding and defining an elongated mold cavity having opposite open ends, this graphite body being provided with an external circumferential surface. A metallic jacket surrounds the graphite body in engagement with the circumferential surface and is subdivided circumferentially of the surface into at least two jacket sections. Pressure means is associated with the jacket sections and is operative for drawing the same together circumferentially of the external circumferential surface to thereby urge the jacket into intimate surface-to-surface contact with the circumferential surface and to subject the graphite body to radially inwardly directed pressure over the entire area of the circumferential surface. Finally, cooling means is provided for cooling the metallic jacket.

Advantageously, the lines of subdivision -that is the lines along which the jacket is subdivided into at'least two jacket sections-extend substantially in parallelism'with the axis of the mold cavity. According to a preferred embodiment adinsert. Advantageously the jacket sections are made from flexible sheet metal and have secured thereto at adjacent locations pressure shoes or the like which cooperate with tensioning screws.

By resorting to my invention, and by tightening the pressure screws or analogous means provided for this purpose, to a larger or smaller extent, it is possible to vary the tensile forces in the metal jacket-and thereby the tangential pressures transmitted by the same into the graphite insert-at will. This means that the mold can be adjusted at the will of an operator in accordance with the requirements of a given operation; moreover, where spring-tensioning means is employed as is preferred in accordance with the present invention, the springs utilized may be so dimensioned and their action so calculated that they compensate for variations in the dimensions of the graphite insert and the jacket sections which occur as a result of temperature fluctuations during operation of the mold.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended BRIEF DESCRIPTION OF THE DRAWING FIG. I is a section taken on the line H of FIG. 2;

FIG. 2 is a section taken on the line lI-II of FIG. 1; and

FIG. 3 is a fragmentary detail in an enlarged sectioned view, of FIG. I. I

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawing the mold cavity is identified with reference numeral I and is outlined and surrounded by a graphite body 2 which in the illustrated embodiment has an oval outer circumferential surface 3.

The outer circumferential surface 3 of the graphite body 2 is surrounded by a metallic jacket which in the illustrated embodiment consists of two jacket sections 4 and 5 each of which covers substantially one circumferential half of the outer circumferential surface 3. A cooling jacket 11 surrounds the mold and is provided with nozzles or openings 7 through which jets of water 6 are ejected onto the metallic jacket consisting of the sections 4, 5 to thereby cool the same. The cooling water 8 which is ejected through the nozzles 7 is supplied through the inlet 9 and leaves through the outlet 10.

FIGS. 2 and 3 show more clearly that the two jacket sections 4, 5-which consist of flexible sheet metal-are drawn together under spring action in circumferential direction of the outer circumferential surface 3 of the graphite body or insert 2. The lines of separation between the jacket sections 4, 5 extent substantially parallel to the longitudinal axis of the mold cavity I. As shown clearly in FIG. 3, edge portions of the jacket sections 4, 5 overlap one another. In the illustrated embodiment this is accomplished by providing the jacket section 5 with an extension or tongue 15 extending in circumferential direction of the surface 3 and which tapers in thickness in this circumferential direction towards its free end. The extension 15 is overlapped by the jacket section 4.

As seen in FIG. 3, the taper of the extension 15 toward s its free end is so flat that in the region of the overlap there is at no point a convex curvature of the metallic jacket consisting of the sections 4, 5 in direction towards the center of the mold cavity. The purpose of this is to assure that the tangential stresses in the sections 4, 5 will result in radial stresses acting upon the graphite insert 2, even in the region of the overlap. To this end it is necessary that the outer overlapped surface 15a of the extension 15 will be located-as seen from the means of whichthey are secured to the sections 4, 5, for instance by welding or the like.- Opening are provided in the flanges l4, l6 and through these openings are extended screws 12 with packets of dished springs 13 being interposed between the flange l4 and the head of the screw 12, and similarly between the flange l6 and the nut threaded onto the opposite end of the screw 12. A plurality of such arrangements are provided axially spaced of the cavity 1. v

' By tightening the screws 12 to a greater or lesser degree, the springs 13 are compressed concomitantly ,and tangential forces exerted drawing the sections 4 and together tangentially of the surface 3. These tangential forces can be adjusted precisely because each individual screw 12 can be tightened to the desired extent so that the tangential forces-and thereby the pressure exerted upon the graphite insert 2-can be varied at will along the axial length of the graphite insert 2, that is along the axial length of the mold cavity 1. As a result of this it is of coursepossible to vary the extent and intimacy of contact between the jacket sections 4, 5 and the outer circumferential surface 3 of the insert 2 by this means.

The taper of the extensions 15 assures that the overlapped portion of the jacket 4 will slide smoothly on the extension 15 so that the jacket consisting of the sections 4, 5 will tightly and without circumferential interruption surround and contact the outer circumferential surface 3 of the graphite insert 2.

Naturally it will be understood that other types of arrangements may be substituted for the screws 12 and the springs 13 without in any way changing or detracting from the invented concept.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a mold for continuous casting of metal, it is not intended to be limited to the 'details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

I claim:

1. A mold for continuous casting of metal, comprising a graphite body surrounding and defining an elongated mold cavity having opposite open ends, said graphite body having an external circumferential surface; a metallic jacket surrounding said graphite body in engatement with said circumferential surface, said jacket being subdivided circumferentially of said surface into at least two jacket sections; pressure means associated with said jacket sections and operative for drawing the same together circumferentially of said surface to thereby urge said jacket into intimate surface-to-surface contact with said circumferential surface and subject said graphite body to radially inwardly directed pressure over the entire area of said circumferential surface, said pressure means, comprising tensioning screws each engaging circumferentially adjacent edge portions of said jacket sections and operative for exerting circumferentially directed tensile forces thereon, and spring means associated with said screws and operative for enabling limited resilient displacement ,of said edge portions with reference to one another; and cooling means for cooling said metallic jacket.

2. A mold as defined in claim 1, said edge portions extending in longitudinal direction of said mold cavity and in at least substantially parallelism with the axis thereof.

3. A mold as defined in claim 1, said edge portions extending. longitudinally of said mold cavity and overlapping one another in circumferential direction of said surface.

4. A mold as defined in claim 3, one of said adjacent edge portions being provided with an extension extending and tapering in circumferential direction of said surface, and the other adjacent edge portion overlapping said extension.

5. A mold as defined in claim 4, wherein said extension has a free and an outer surface tapering in direction towards said free tip, said. outer surface being located in the area defined between said circumferential surface and an imaginary tangential plane intersecting both said outer surface and tip.

6. A mold as defined in claim 1, wherein said jacket sections consist of sheet metal.

7. A mold as defined in claim 1, wherein said jacket sections consist of flexible sheet metal.

8. A mold as defined in claim 7, wherein said edge portions overlap and are each provided with nut means, and screw means threaded into said nut means for drawing said edge portions together in circumferential direction of said surface. 

1. A mold for continuous casting of metal, comprising a graphite body surrounding and defining an elongated mold cavity having opposite open ends, said graphite body having an external circumferential surface; a metallic jacket surrounding said graphite body in engatement with said circumferential surface, said jacket being subdivided circumferentially of said surface into at least two jacket sections; pressure means associated with said jacket sections and operative for drawing the same together circumferentially of said surface to thereby urge said jacket into intimate surface-to-surface contact with said circumferential surface and subject said graphite body to radially inwardly directed pressure over the entire area of said circumferential surface, said pressure means comprising tensioning screws each engaging circumferentially adjacent edge portions of said jacket sections and operative for exerting circumferentially directed tensile forces thereon, and spring means associated with said screws and operative for enabling limited resilient displacement of said edge portions with reference to one another; and cooling means for cooling said metallic jacket.
 2. A mold as defined in claim 1, said edge portions extending in longitudinal direction of said mold cavity and in at least substantially parallelism with the axis thereof.
 3. A mold as defined in claim 1, said edge portions extending longitudinally of said mold cavity and overlapping one another in circumferential direction of said surface.
 4. A mold as defined in claim 3, one of said adjacent edge portions being provided with an extension extending and tapering in circumferential direction of said surface, and the other adjacent edge portion overlapping said extension.
 5. A mold as defined in claim 4, wherein said extension has a free and an outer surface tapering in direction towards said free tip, said outer surface being located in the area defined between said circumferential surface and an imaginary tangential plane intersecting both said outer surface and tip.
 6. A mold as defined in claim 1, wherein said jacket sections consist of sheet metal.
 7. A mold as defined in claim 1, wherein said jacket sections consist of flexible sheet metal.
 8. A mold as defined in claim 7, wherein said edge portions overlap and are each provided with nut means, and screw means threaded into said nut means for drawing said edge portions together in circumferential direction of said surface. 